Duplicate content is a problem for many sites, often the site owner does not even realize his/her site has this problem and is being penalized by Google and other search engines, whilst loosing valuable PageRank.
There are some very good reasons why you should seriously consider SEO before you start building a website.
More often than not, website projects are started without prior keyword research. The information architecture and overall structure are built, and SEO is relegated to 'phase 2', for AFTER the website is finished.
Internet marketing is gradually becoming a fixed feature of the marketing budgets in Australia and companies are spending their money more wisely by investing in Search Engine Optimisation to improve their rankings on Google and achieve top search engine placement.